Moparts

340 T/A crank?

Posted By: RapidusMaximus

340 T/A crank? - 08/18/22 05:10 PM

Can anyone confirm if this crank is or is not a T/A crank, I’ve googled and can’t seem to confirm, the guy I got it from says it’s a TA, one of my small block buddies says it’s a 318…what say yee Moparts gurus???

Attached picture F696868B-86AA-4C70-8556-DC6962FF30E9.jpeg
Attached picture D01F97C3-A143-46DE-88ED-31EE573EFE48.jpeg
Attached picture 56604123-A12A-4E02-936A-5E5882D322D2.jpeg
Posted By: Sunroofcuda

Re: 340 T/A crank? - 08/18/22 05:34 PM

I'll add to your question here since I own an AAR. Is the T/A-AAR crank a different crank than a regular 1970 340? I've never heard that the cranks were any different!
Posted By: moparx

Re: 340 T/A crank? - 08/18/22 05:43 PM

in that year, i thought the 318 and 340 cranks were the same ? shruggy
i have been wrong eleventybillion times in my life, so one more time being wrong wouldn't be a surprise...............
beer
Posted By: John_Kunkel

Re: 340 T/A crank? - 08/18/22 06:17 PM

68-72 340 forged 2532457, 2843868 (#1 and #4 rod journal drilled through)

Parts book shows no difference for T/A.
Posted By: Mopar Mitch

Re: 340 T/A crank? - 08/18/22 08:01 PM

The radius ends look really questionable... T/A and AAR factory cranks were just standard 340 forged cranks.

Race-305 T/A cranks are another story.
Posted By: Cab_Burge

Re: 340 T/A crank? - 08/19/22 12:05 AM

Originally Posted by moparx
in that year, i thought the 318 and 340 cranks were the same ? shruggy
i have been wrong eleventybillion times in my life, so one more time being wrong wouldn't be a surprise...............
beer

I have heard that the 340 cranks have bigger counterweights for the heavier bigger bore 340 pistons, not the same as 318 tsk
I have seen 318 cranks used in 340 motor with steel plates welded on the crank counterweights for increasing the weight for balancing work shruggy
If they both had the same casting number, I might believe there the same but when they aren't there is a reason for that work
BTW, I have used a 318-3 HD truck crank in a 340 race motor with really light SS pistons, that worked really well up
Posted By: fastmark

Re: 340 T/A crank? - 08/19/22 08:17 AM

I’ve got lots of 340s apart. I can’t say that I have ever looked for the number on the forging on a 340. I've got a real TA motor apart right now and can look for a number. There is no difference in the part number, as stated several times, in all forged 340 cranks. All 340 cranks had the rod journal end drilled to remove weight for balancing. All 273 and 318-3 steel cranks did not have the journal drilled. It is solid. Therefore it changes the balance. 273 and 318-3 used the same steel crank. The 273 used a very thick wall piston pin to make the balance work for the same crank. My understanding is that all the counter weight throws were the same on all 273-340 steel cranks. Sadly, that crank looks rusted beyond use. It’s not a special crank.
Posted By: RapidusMaximus

Re: 340 T/A crank? - 08/19/22 03:08 PM

Originally Posted by fastmark
I’ve got lots of 340s apart. I can’t say that I have ever looked for the number on the forging on a 340. I've got a real TA motor apart right now and can look for a number. There is no difference in the part number, as stated several times, in all forged 340 cranks. All 340 cranks had the rod journal end drilled to remove weight for balancing. All 273 and 318-3 steel cranks did not have the journal drilled. It is solid. Therefore it changes the balance. 273 and 318-3 used the same steel crank. The 273 used a very thick wall piston pin to make the balance work for the same crank. My understanding is that all the counter weight throws were the same on all 273-340 steel cranks. Sadly, that crank looks rusted beyond use. It’s not a special crank.

Yeah, it’s already 10/10, I have some other parts to take to the machine shop, I’m going to carry this thing with me see if it’s savable. The journals are still smooth…maybe??? It will clean up…maybe luck
Posted By: TJP

Re: 340 T/A crank? - 08/19/22 03:16 PM

Originally Posted by RapidusMaximus

Yeah, it’s already 10/10, I have some other parts to take to the machine shop, I’m going to carry this thing with me see if it’s savable. The journals are still smooth…maybe??? It will clean up…maybe luck


iagree
Posted By: lilcuda

Re: 340 T/A crank? - 08/19/22 03:28 PM


Guys, the simple way to tell is to look at the front and rear crank throws. 340s have a hole bored in the end throws to make it possible to balance it with the heavier 340 rods. This crank appears to have the front throw bored, so it's a a pretty good assumption that the rear is as well. Also, I believe all forged 340 cranks were shot peened, so if you look closely at the radii of the journals, you can sometimes see it. I do not know for sure if 318 truck cranks are shot peened. Actually, now that I think about it, I wonder if the 318 trucks had the heavier 340/360 rods as well? Quite frankly, unless you must have absolutely every part be the correct casting/forging #, I'm not sure it matters. If it is a forged, shot peened crank that has the end throws bored and it is is in good shape, run it.
Posted By: lilcuda

Re: 340 T/A crank? - 08/19/22 03:30 PM

Originally Posted by fastmark
I’ve got lots of 340s apart. I can’t say that I have ever looked for the number on the forging on a 340. I've got a real TA motor apart right now and can look for a number. There is no difference in the part number, as stated several times, in all forged 340 cranks. All 340 cranks had the rod journal end drilled to remove weight for balancing. All 273 and 318-3 steel cranks did not have the journal drilled. It is solid. Therefore it changes the balance. 273 and 318-3 used the same steel crank. The 273 used a very thick wall piston pin to make the balance work for the same crank. My understanding is that all the counter weight throws were the same on all 273-340 steel cranks. Sadly, that crank looks rusted beyond use. It’s not a special crank.


I should have read your reply before I posted. You are correct. up
© 2024 Moparts Forums